Oil or thermal cut-out.



0. PRATT. OIL 0R THERMAL GUT-OUT.

APPLICATION I'ILEI) JUNE 6, 1907.

Pgtented Dec. 29, 1908.

2 SHEETS-QBEET 1.

I wan homo flttoumqa G. N. PRATT.

OIL OR THERMAL GUT-OUT. APPLIOATION FILED JUNE 6 1907.

907,872. Patented. Dec;29,1908.

2 SHEETS-SHEET 2.

. rent will be with the upper are.

CHARLES N. PRATT, OF ROCHESTER, NEW YORK.

OIL OR THERMAL CUT-OUT.

Specification of Letters Patent.

ZEatented Dec. 29, 1908.

Application filed .Tune 6, 1907. Serial No. 377,56

ToaZZ whom it may concern:

Be it known that 1, CHARLES N. PRATT, a citizen of the United States,residing at Rochester, inthe county of Monroe and State of New York,have invented certain new and useful Improvements in Oil or Thermal Cut-Outs, and do declare the following to be a full, clear, and exactdescription of the invention, such as will enable others skilled in theart'to whichit appertains tomake and use the same.

This invention relates to electrical switches, and more particularly tothat class of such switches that are provided with a fuse, and it hasfor its object to proride means whereby the are or flash caused by themelting or destruction of the fuse from an excessive curextinguished byoil or other liquid.

Broadly s eaking, the invention com rises a box or'ot 1er receptaclewithin whic the fuse may be submerged in a liquid, as oil.

The receptacle is substantially hermetic ally sealed and in itspreferred form the lid or cover of the receptacle is provided with oneclosing of the lid will break or close the switch as the-case may be. Avent pipe is preferably provided which communicates portion of thereceptacle and is proxided wit suitable means for closing it, as atrap,which is adapted to be filled with oil or other suitable liquid.

In the accompanying drawings, which illustrate the intention, Figure 1is a top plan view ofthe box containing the switch, showing the co erremoved or swung to one side upon its hinges; Fig. 2 is a longitudinalsec-.

. tional view of the box closed; Fig. 3 is a cross sectional ".iew takenon the line 3 3 of Fig. 2; Fig. 4 is a'longitudinal section takenthrough the switch block on the cover; and Figs. 5 and 6 are pets ectihedetail news of the'bla'des of the switc Referring more particularly tothe drawings, 1 indicates abox or receptacle which may be of any shapeor form, preferably rectangular, with a removable cover, The coier ispreferably hinged to the box at one end by. means of perforated ears, 3,and pintles, 4. The cover is adapted to be held or locked in its closedposition by means of hinge bolts, -5, which are adapted to engage withprojections, v6, upon the edge of the cover in the ordinary'manner. Asuitable packing or gasket, 7, preferably of yielding the box forsealing the box. The box and its cover may be'forrned of any suitablematerial, preferably of metal or insulating mate rail, and, is adaptedto contain oil or other liquid, indicated at 8, which fills the box orrece tacle nearly to the top.

The receptacle is preferably provided with brackets or arms, 9, by meansof which it may be secured in any position, and it is pro vided at itsends with openings, 10, which are preferably surrounded with internallyscrewthreaded projections, 11, through which the conductors, not shown,may be inserted. A hollow nut, 12, fits in the projection 11 and isadapted to clamp the forward end of a covering, 13, for the weir betweenits forward end and the side of the receptacle. The openings, 10, arereferably located directly opposite each ot 1G1 and in alinement witheach other at the ends of the box.

Secured to the interior of the boxin any desired manner, preferably uponthe bottom, is a block, 14, of insulating material, as hard wood.Secured to the ends of the block 14 are terminals, 15, for theconducting wires,

each of which is preferably provided with a clamping portion, 16, bymeans of which the wire or conductor is secured in said terminals bymeans of a screw, 17. One or more knife blade contacts, 18, are securedto the blocks 15 in any desired manner so as to roject forwardly towardthe lid or cover of the box. The terminals 15 are located substantiallyin alinement with the'openings 10 in the ends of the box, whereby theconductors may be easily inserted in said terminal blocks after havingbeen passed through the openings, 10.

Secured upon the inner side of the cover is a block 19, of insulatingmaterial, as hard wood, which is recessed upon its upper side as shownat 20, and provided with two diverging perforations 21, leading from thebottom of said recess to the lower edge of the, block. Each end of theblock 19 is rematerial, is placed between the cover and cessed upon itslower side as shown at 22,.

in which is seated contact supports, 23.

The distance between the recesses 22 is sufficient to permit the lowerportion of the block 19 to pass down vbetween the knife blades, 18, and.each contact support, 23, 1s provided with one, or more knife bladecontacts, 24, which are adapted to be forced into engagement with thecontacts 18, and thereby estabhsh electrical connection when the coverof the box is closed. The inner edge of one of the contacts 18, wherethe contacts 24 on the free or swinging end of the cover engagetherewith, is preferably cut 5 away as shownat 25.

Projecting through the perforations 21 in the block 19 is laced thefuse, 26, which has its center or oubled portion extending up into therecess 20, and has its free ends connected with the lower portion of thecontact supports 23 by means of clamping screws, 27, in the usualmanner.

The rear wall of the box is provided with a vertical channel or conduit,28, which com- 5 municates with the interior of the box through a recess29 formed in the cover by raisin directly of the cover being alsoextended out over 0 the conduit,'28, as shown at 31. The conduit 28 isextended at the lower end as by means of a pipe 32, which is removablysecured therein and has its lower end formed into a trap, 33, as bybeing curved upward or bent into a substantial U-shape the length andsize of the trap being. suflicient to prevent the seal from being blownout by theexplosion caused by the melting of the fuse. The box is alsoprovided with avplug, 30 34, at or near the bottom by means of which thebox may be emptied of its liquid contents at any time.

In using a switch as above described, the

conductors are connected with the terminal The box is t en filled withoil, or other suitable liquid nearly to the top, or preferably untilit'will stand above the upper ends of the 40 perforations, 21, in thebottom of the recess,

20. The cover of the box is then closed which will immediately close theswitch by causing the contacts 24 to engage with g the .contacts- 18.The trap 33 is also filled with oil or other liquid and the switch is incomplete working order.

If 'atany time, the current should become so excessive as to melt thefuse, the are formed at the time of such melting or fusing Will beextinguished by the oil or other liquid, and the danger from fire fromsuch flashing of the fuse will be absolutely prevented. Any expulsion ofthe air that may take place due to 'the heat developed by thevolat1lization will be permitted to pass down through the conduit at therear of the box and be allowed to expand its fQIQflQI energy through theseal in the trap'; As the trap remains closed at all times and reventsthe entrance of explosive gases or ot or mixtures to the interior of thebox, as well as permitting the arc gases to escape or to pass out of thebox, the switch is eculiarly adapted for use in subways, manoles, etc.,which areliable to have gas collect therein, and as the a portion of thecover as shown at 30 over the partition wall, the edge presence of waterwill only more effectively close the trap by increasing the amount ofliquid therein, the use of the switch is also peculiarly adapted forplaces which are liable to be submerged or flooded from excessive water.'I he sealing of the box also renders the switch peculiarly adaptablefor use in places which are subject to overflow.

As above described, it will be seen that the switch is very simple andeffective as it can be quickly secured in any desired position by meansof the brackets, and as quickly removed if desired. The fuse can beeasily inserted with or without removing the block from the cover, therecess in its upper edge permitting of the latter, and by means of thegasket and packing, and the hinge bolts, an absolutely tight joint canbe eil'ected between thecover and the box. The size and dimension of thebox and other accessories can be made in accordance with the capacity ofthe current to be handled, thereby adapting it for use upon all lines orconductors, irrespective of their capacity. A sufiicient portion of thefuse extends above the surface of the liquid in the box to permit of itsbeing fused in the air while the presence of the oil or liquidextinguishes the are formed thereby. Ihe opening of the boxautomatically opens the switch and thereby removes all danger ofaccidental contact with a completed circuit, and the box can be formedof any desired material as treated wood, porce- .lain, glass, or otherinsulating material of 35 blocks 15 and the fuse is connected with thecontact sup orts 23, while the box is open.

high resistance. The incoming cables or conductors can be rovided withinsulation of any kind that will not be affected by the oil or liquidwithin the box, and when the box is used overhead, the seal could beomitted.

The openings 10 are made oil tight in any desired manner but may be sorendered as follows: Within the projection 11 is a packing 35 which maybe of lead or similar metal bearing against the flange 36 around theopening 10. Within said packing, said opening and in the tube 12 isplaced a plug 37 of insulating material surrounding the conductor 38.Abutting against the outer end of the plug 37 is the insulating covering39 of the conductor 38,-over this insulation is the usual lead pipe 40of an armored conductor, the pipe 40 and the tube 12 being secured together by a wipe connection 41.

Having described my invention, I claim: 1. In a switch, areceptacleadapted to contain a liquid and provided with means for making andbreaking a circuit under the liquid when the lid is actuated, and aconduit communicating with the interior of the rece tacle above thesurface of the liquid t e outer end of the conduit being yieldablysealed. 7 v 2. In a switch, a receptacle adapted to contain a liquid,one wall of the rece tacle being provided with a conduit and the idbescrew connecting with the space (We said liquid whereby a passage isprovided for the expulsion of the air from the receptacle, said conduitleading downwardly and being prcvided with a U-shaped portion. adapted.to hold a liquid and to form'ayieldahle seal. 4. In a switch'areceptacle adapted to contain a liquid, means for n: airing andbreakingv a circuit within the receptacle, one wall of r the receptaclebeing provided with a vertical conduit and the covcrcf said receptaclebeing recessed and extending laterally over said conduit to establishcommunication-between the conduit and 'a portion of the interior of therace tacle above the liquid, a 'pipe extending om the lower end of saidconduit and having its lower end upturned to form a trap,said trap beingadapted to hold a liquid. 5Q Ina swltch a receptacle adapted to containa liquid, means for making and breaking a circuit within saidreceptacle, one. wall of said receptacle being provlded with a verticalconduit and the cover of said receptacle being recessed and extendinglaterally over said conduit to establish communication between theconduit and a portion of the interior of the rece tacle above theliquid, an outwardly 'cldab e; valve eommumcating with ower end of saidconduit.

vIn testimony'whereof I have hereunto set my. hand in presence of twosubscribing witnesses. 4

CHARLES N. PRATT.

Witnesses:

GEORGE HEARN, E. E. LAZIER.

the I

